Statistical-thermodynamic description of the order-disorder transformation of D019-type phase in Ti-Al alloy
Résumé
Within the framework of the self-consistent field approximation and the static concentration waves approach, a statistical-thermodynamic description of D019-type superstructure in Ti-Al alloy is developed. A model of order-disorder phase transformation is applied for the non-stoichiometric intermetallic Ti3Al phase. Interatomic-interaction parameters are estimated for both approximations. One model supposes temperature-independent interatomic-interaction parameters, while the other includes the temperature dependence of mixing energies. The partial phase diagrams (equilibrium compositions for the coexistent ordered α2-phase and disordered α-phase) are evaluated for both cases. \textcopyright 2007 Elsevier B.V. All rights reserved.